In many industrial sectors it is necessary to transform reels of web material of one size into spools of a different size, by means of a process of unwinding parent reels, or so-called jumbo reels, and rewinding them into spools with different size characteristics. In some cases the web material from a single parent reel is unwound and divided into longitudinal strips, each of which is wound onto a helically wound spool. The finished spools obtained in this way are used as semi-finished products to feed production lines for other articles.
Machines that produce spools of helically wound web material from parent reels are sometimes known as spooling machines. The web material can, for example, be a non-woven fabric. The helically wound spools that are obtained are used, for example, to feed machines for the production of sanitary towels, diapers and other hygienic and sanitary articles. The web material wound on the parent reels sometimes has a transversal size (corresponding to the axial dimension of the parent reel) 5-15 times the width of the individual longitudinal strips that are obtained by longitudinal cutting the web material on the parent reels. The individual strips are fed simultaneously to helical winding stations, in each of which a helically wound spool is formed. The winding stations are arranged in line one after the other in a machine direction, defined by the direction of advance of the longitudinal strips obtained by cutting the material on the parent reels. Each strip is fed to the respective winding station along a feed path.
As the web material in a single parent reel is subdivided into a plurality of strips, and as these are helically wound onto the helically wound spools, on which a large quantity of cut material can thus accumulate, the helically wound spool production cycle requires the use of a plurality of parent reels. In other words, if the web material from the parent reels is subdivided into N longitudinal strips, for simultaneous formation of N helically wound spools, in order to form the N helically wound spools a certain number M of parent reels will be required, where M is usually higher than 1, typically between 2 and 10, for example between 2 and 8, in certain cases between 2 and 6.
When a first parent reel finishes, it must be replaced by a second parent reel, and the trailing edge of the first web material coming from the first parent reel must be spliced to the leading edge of the second web material wound on the second parent reel. To reduce the time required to replace a parent reel, when it is finishing, with a new parent reel, the unwinding section of the machine usually comprises two unwinding stations, working alternately, and a welding station to weld the trailing edge of a first web material, coming from a first parent reel that is finishing, to the leading edge of a second web material, coming from a new parent reel that is standing-by.
The parent reels are cumbersome and heavy, and require complex operations to load them onto the unwinding stations.
There is consequently a need to optimize the loading operations for the parent reels, making them simpler and faster, in particular but not exclusively as regards spooling machines, for the production of helically wound spools.